Data storage subsystems comprise highly reliable means for storage and accessing of data. Automated data storage library subsystems provide storage of large numbers of data storage media and typically have numbers of data storage drives, and may provide caches and other intermediate storage to migrate data to, and access data from, the data storage media. When errors may occur, it is desirable to both insure against the loss of data and to insure against unnecessary removal and replacement of either data storage media or data storage drives, and to avoid the time necessary to update the subsystem and/or the data. It is also desirable to insure against unnecessary service calls, and to avoid potential downtime that might result. This means that it is desirable to automatically oversee error events and conduct removals, replacements, and provide service calls when necessary.